Liquid crystal display having openings in the protective layer and gate insulating layer and method for fabricating the display

ABSTRACT

The present invention relates to a liquid crystal display and a fabricating method thereof. The cell gaps for the red, green and blue pixel areas are formed in a separate manner for correcting the color shift to enhance image quality. Openings for controlling the cell gaps are provided in the protective layer and the gate insulating layer and have a zigzag-shaped boundary. In this way, the light leakage near the boundary of the openings can be prevented.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 10/499,131, filed Dec. 23, 2004 now U.S. Pat. No. 7,463,321,which is a National Stage filing under 35 U.S.C. §371 of InternationalPatent Application PCT/KR02/01390, filed Jul. 24, 2002, which claimspriority to Korean Patent Application No. 2002-2229, filed Jan. 15,2002, and Korean Patent Application No. 2002-25537, filed May 9, 2002,the contents of which are herein incorporated by reference in theirentirety.

BACKGROUND OF THE INVENTION

1. Technical Field

The present disclosure relates to a liquid crystal display and, morespecifically, to a liquid crystal display having openings in theprotective layer and gate insulating layer and a method for fabricatingthe same.

2. Discussion of Related Art

Generally, a liquid crystal display (LCD) has top and bottom panels withelectrodes, and a liquid crystal material interposed between the twopanels. Electric fields are applied to the liquid crystal material bymeans of the electrodes, and controlled in the strength to control thetransmittance of light passing through the panels, thereby displayingthe desired picture images.

Among the LCDs, has been now extensively used a display device havingtwo panels respectively provided with a common electrode and a pluralityof pixel electrode, and the panel with the pixel electrodes includes aplurality of thin film transistors (TFTs) for switching the voltageapplied to the pixel electrodes.

In the LCD, the transmittance of blue light having short wavelength ishigh at low gray scales, while the transmittance of red and green lightsbecomes large as goes to higher gray compared with that of the bluelight. Therefore, as it goes to higher gray, the component of yellowlight, which is obtained by synthesizing red and green lights, becomeslarge to yield color shift such as so-called yellowish phenomenon anddeterioration of image quality. Furthermore, the variation in thetransmittance of lights with different wavelength depending on theviewing angle is not uniform. This also affects the color shift todeteriorate the image quality.

SUMMARY

It is a motivation of the present invention to enhance the image qualityby correcting the color shift.

It is another motivation of the present invention to prevent increase inthe light leakage due to the structural variation for the color shiftcorrection.

These and other motivation may be realized by separately providing cellgaps for the red, green and blue pixel areas.

Specifically, a thin film transistor array panel for the liquid crystaldisplay is provided, which includes a first insulating substrate; aplurality of gate lines formed on the first insulating substrate; a gateinsulating layer covering the gate line; a plurality of data linesformed on the gate insulating layer and intersecting the gate lines todefine first to third pixel areas; a plurality of thin film transistorselectrically connected to the gate lines and the data lines; aprotective layer covering the thin film transistors and the data linesand having a plurality of contact holes exposing a plurality of drainelectrodes of the thin film transistors; and a plurality of pixelelectrodes connected to the drain electrodes through the contact holes,wherein the protective layer and the gate insulating layer have openingsin the first and the second pixel areas, and the openings overlap thepixel electrodes and have zigzag-shaped boundaries.

A portion of the gate insulating layer overlapping a semiconductorpattern may be thicker than other portions of the gate insulating layer.The pixel electrode may include a plurality of partitions by means ofcutouts, and the openings may include a plurality of sub-portionsoverlapping the partitions of the pixel electrodes. The boundary of theopening may make angle of about zero degree, about 45 degrees, about 90degrees and about 135 degrees with the gate lines.

A liquid crystal display including the thin film transistor array panelis provided, which includes a second insulating substrate facing thefirst insulating substrate; a black matrix formed on the secondinsulating substrate; red, green and blue color filters arranged in turnon the black matrix and the second insulating substrate and facing thefirst to the third pixel areas; and a common electrode covering thecolor filters.

One of the red, green and blue color filters may be thicker than theother color filters. The cell gaps D1, D2 and D3 in the first, thesecond and the third pixel areas may satisfy the relation, D1>D2>D3, orD1=D2>D3. An overcoat is formed between the common electrode and thecolor filters, and the common electrode may have a plurality of cutouts.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the present disclosure and many of theattendant aspects thereof will be readily obtained as the same becomesbetter understood by reference to the following detailed descriptionwhen considered in connection with the accompanying drawings, wherein:

FIG. 1 is a layout view of a TFT array panel for a LCD according to afirst embodiment of the present invention;

FIG. 2 is a layout view of a color filter array panel for the LCDaccording to the first embodiment;

FIG. 3 is a front layout view of cutouts of a pixel electrode and acommon electrode of the LCD according to the first embodiment;

FIG. 4 is a sectional view of FIG. 3 taken along the line IV-IV′;

FIG. 5 is a sectional view of an LCD according to a second embodiment ofthe present invention taken along the line corresponding to the lineIV-IV′ shown in FIG. 3;

FIGS. 6A to 6E are sectional views of the TFT array panel for the LCDaccording to the first and the second embodiments taken along the linescorresponding to the lines VI-VI′, VI′-VI″ and VI″-VI′″ shown in FIG. 1,which sequentially illustrates the steps of fabricating the TFT arraypanel;

FIG. 7 is a layout view of a LCD according to a third embodiment of thepresent invention; and

FIG. 8 is a cross sectional view of the LCD shown in FIG. 7 taken alongthe line VIII-VIII′.

DETAILED DESCRIPTION OF THE DRAWINGS

In describing exemplary embodiments of the present disclosureillustrated in the drawings, specific terminology is employed for sakeof clarity. However, the present disclosure is not intended to belimited to the specific terminology so selected, and it is to beunderstood that each specific element includes all technical equivalentswhich operate in a similar manner.

DESCRIPTION OF THE REFERENCE NUMERALS

-   121: Gate line,-   171: Data line,-   131: Storage electrode line,-   133 a, 133 b, 133 c, 133 d, 133 e, 133 f: Storage electrode-   190 (190 a, 190 b, 190 c): Pixel electrode,-   140: Gate insulating layer-   180: Protective layer,-   A, B, C: Opening-   3: Liquid crystal layer,-   220: Black matrix-   230 (R, G, B): Color filter,-   270: Common electrode,-   270 271, 272, 273: Cutout

The present invention now will be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Like numerals refer to like elementsthroughout.

In the drawings, the thickness of layers and regions are exaggerated forclarity. Like numerals refer to like elements throughout. It will beunderstood that when an element such as a layer, region or substrate isreferred to as being “on” another element, it can be directly on theother element or intervening elements may also be present. In contrast,when an element is referred to as being “directly on” another element,there are no intervening elements present.

Then, liquid crystal displays according to embodiments of the presentinvention will be described with reference to the drawings.

As described above, the color shift is generated since the variation inthe transmittance of lights with different wavelengths is not uniform.Therefore, if the variation in the light transmittance is separatelycontrolled for respective wavelengths, the desired color correction canbe made to prohibit the color shift.

The light transmittance of an LCD depends upon the retardation Δn·d(where Δn indicates a birefringence and d indicates a cell gap), and thelight wavelength λ. That is, the light transmittance varies dependingupon the retardation and the degree of the variation depends upon thelight wavelength. The dependency of the light transmittance upon theretardation and the light wavelength can be discriminated from thefollowing equation:

$\begin{matrix}{I = {I_{0}\sin^{2}2\;\theta\;{\sin^{2}\left( \frac{\pi\; d\;\Delta\; n}{\lambda} \right)}}} & (1)\end{matrix}$

In the LCD, the birefringence Δn in red, green and blue pixel regions isequal to each other since the pixel regions contain the same liquidcrystal. Accordingly, only the cell gap can be used to separatelycontrol the light transmittance in the respective red, green and bluepixel regions. Therefore, the color shift problem due to the non-uniformvariation in the transmittance of the red, the green and the blue lightscan be compensated by determining the cell gap for respective pixelregions in a separate manner to individually control the lighttransmittance. The wavelength of the blue light is the shortest, that ofthe green light is the next, and that of the red light is the longest.In view of Equation 1, the cell gap, therefore, gradually increases fromthe blue region to the red region via the green region. That is, thecell gap is made as follows:d_(blue)<d_(green)<d_(red)  (2)

Now, LCDs according to embodiments of the present invention aredescribed in detail with reference to the drawings.

FIG. 1 is a layout view of a TFT array panel for an LCD according to afirst embodiment of the present invention, and FIG. 2 is a layout viewof a color filter array panel for an LCD according to a first embodimentof the present invention. FIG. 3 is a layout view showing arrangement ofcutouts of a pixel electrode and a common electrode for an LCD accordingto a first embodiment of the present invention, and FIG. 4 is asectional view of the LCD shown in FIG. 3 taken along the line IV-IV′.

A TFT array panel for an LCD according to a first embodiment of thepresent invention is described with reference to FIGS. 1 and 4.

A plurality of gate lines 121 extending in a transverse direction and aplurality of storage electrode lines 131 extending parallel to the gatelines 121 are formed on an insulating substrate 110 preferably made oftransparent glass. A plurality of gate electrodes 123 are protruded fromthe gate lines 121 and a gate pad 125 is provided at one end of eachgate line 121.

A plurality of sets of first to fourth storage electrodes 133 a, 133 b,133 c and 133 d as well as a plurality of storage electrode connectors133 e and 133 f are connected to each storage electrode line 131. Thefirst storage electrode 133 a is directly connected to the storageelectrode line 131 and extends in a longitudinal direction. The secondstorage electrode 133 b and the third storage electrode 133 c areconnected to the first storage electrode 133 a and extend in thetransverse direction. The fourth storage electrode 133 d is connected tothe second and the third storage electrodes 133 b and 133 c and extendsin the longitudinal direction. The storage electrode connectors 133 eand 133 f interconnect the fourth storage electrode 133 d and the firststorage electrode 133 a in an adjacent pixel area.

The gate wire 121, 123 and 125 and the storage electrode wire 131 and133 a to 133 f are made of a conductive material such as Al, Al alloy,Cr, Cr alloy, Mo, Mo alloy, chromium nitride and molybdenum nitride andhave a thickness of 1,000-3,500 Å.

The gate wire 121, 123 and 125 and the storage electrode wire 131 and133 a to 133 f may have a multiple-layered structure. In this case, itis preferable that at least one layer is made of a metal with lowresistivity.

A gate insulating layer 140 is formed on the gate wire 121, 123 and 125and the storage electrode wire 131 and 133 a to 133 f. The gateinsulating layer 140 is made of an insulating material such as siliconnitride or silicon oxide and has a thickness of 3,500-4,500 Å.

An amorphous silicon layer 151 and 153 is formed on the gate insulatinglayer 140 opposite the gate electrodes 123. The amorphous silicon layerincludes a plurality of data line portions 153 and a plurality ofchannel portions 151 and has a thickness of 800-1,500 Å.

An ohmic contact layer 161, 163 and 165 preferably made of amorphoussilicon heavily doped with n-type impurity such as phosphorous P isformed on the amorphous silicon layer 151 and 153. The ohmic contactlayer 161, 163 and 165 bears a thickness of 500-800 Å.

A plurality of source and drain electrodes 173 and 175 are formed on theohmic contact layer 163 and 165. A plurality of data lines 171 extendingin the longitudinal direction are formed on the data line portion 161 ofthe ohmic contact layer. The source electrode 173 is connected to thedata line 171. A plurality of data pads 179 are provided at one ends ofthe respective data lines 171. The data wire 171, 173, 175 and 179 ismade of a conductive material such as Al, Al alloy, Cr, Cr alloy, Mo, Moalloy, chromium nitride and molybdenum nitride and has a thickness of1,500-3,500 Å.

The data wire 171, 173 and 175 may have a multiple-layered structure. Inthis case, it is preferable that at least one layer is made of a metalwith low resistivity.

A protective layer 180 is formed on the data wire 171, 173 and 175 andhas a plurality of contact holes 181 exposing the drain electrodes 175.The protective layer 180 is made of an insulating material such assilicon nitride or silicon oxide and has a thickness of 1,500-2,500 Å.Furthermore, the protective layer 180 may be made of an organicinsulating layer, or a low dielectric CVD layer. The low dielectric CVDlayer may be made of a-Si:C:O or a-Si:O:F, which is deposited by plasmaenhanced chemical vapor deposition (PECVD).

The protective layer 180 and the gate insulating layer 140 have openingsA, B and C with saw-toothed edges. The openings A, B and C are formed byremoving portions of the protective layer 180 and the gate insulatinglayer 140 by etching.

A plurality of pixel electrodes 190 connected to the drain electrodes175 through the contact holes 181 are formed on the protective layer180. The pixel electrodes 190 are made of a transparent conductivematerial such as indium tin oxide (ITO) or indium zinc oxide (IZO).

The pixel electrode 190 includes first to third partitions 190 a, 190 band 190 c, which are connected to each other via a plurality ofconnectors 190 d, 190 e and 190 f. The first partition 190 a is placedat an upper half part or a lower half part of a pixel area defined byintersections of two gate lines 121 and two data lines 171 and has ashape of a rectangle with four chamfered corners. The second and thethird partitions 190 b and 190 c are placed at the other half part ofthe pixel area and have shapes of rectangles with chamfered corners. Thesecond partition 190 b is connected to the first partition 190 a throughthe first and the second connectors 190 d and 190 e, and the thirdpartition 190 c is connected to the second partition 190 b through thethird connector 190 f. The second storage electrode 133 b is disposedbetween the first and the second partitions 190 a and 190 b, and thethird storage electrode 133 c is disposed between the second and thethird partitions 190 b and 190 c. The first and the fourth storageelectrodes 133 a and 133 d are disposed between the pixel electrode 190and the data line 171. Edges of the first partition 190 a extendingparallel to the data lines 171 are longer than its edges extendingparallel to the gate lines 121, while edges of the second and the thirdpartitions 190 b and 190 c extending parallel to the data line 171 areshorter than their edges extending parallel to the gate line 121. Thesecond and the third partitions 190 b and 190 c overlap the first andthe fourth storage electrodes 133 a and 133 d, while the first partition190 a does not overlap the first and the fourth storage electrodes 133 aand 133 d.

The partitions 190 a, 190 b and 190 c of the pixel electrodes 190 in redand green pixel areas overlap the openings A, B and C provided in theprotective layer 180 and the gate insulating layer 140 such that thepartitions 190 a, 190 b and 190 c contact the substrate 110 in theopenings A, B and C. The openings A, B and C are not provided for theblue pixel area such that the pixel electrode 190 on the blue pixel areais placed on the protective layer 180.

The neighboring pixel electrodes 190 across the data line 171 havereversed shapes along the longitudinal direction. That is, referring tothe figures, the first partition 190 a in the first pixel area is placedin the lower half part, while that in the second pixel area is placed inthe upper half part. Consequently, the second and the third storageelectrodes 133 b and 133 c in the two pixel areas across the data line171 are reversed in their positions. However, the TFTs of the pixelareas in a row are connected to the same gate line 121. Therefore, thedrain electrode 175 of the TFT in the first pixel area is connected tothe first partition 190 a, while that in the second pixel area isconnected to the third partition 190 c.

Meanwhile, the electric potential applied to a common electrode in acolor filter array panel is also applied to the storage electrode line131, the storage electrodes 133 a to 133 d, and the storage electrodeconnectors 133 e and 133 f.

As described above, a storage line or a storage electrode receiving thecommon electric potential and disposed between the data line and thepixel electrode or between the gate line and the pixel electrodeprevents the potentials of the data line and the gate line fromaffecting the electric field of the pixel area, thereby forming stabledomains.

In this way, the pixel electrodes 190 in the red and green pixel areasare formed directly on the insulating substrate 110, while the pixelelectrode 190 in the blue pixel area is formed on a lamination of thegate insulating layer 140 and the protective layer 180. Therefore, thepixel electrodes 190 in the red and the green pixel areas and the pixelelectrode 190 in the blue pixel area have height difference by thethickness of the protective layer 180 and the gate insulating layer 140,i.e., by about 0.5-0.7 microns.

This structure makes a step of about 0.5-0.7 microns between the bluepixel area and the red and green pixel areas.

Meanwhile, the boundaries of the openings A, B and C have saw-toothededges making angle of about 45 degrees with the gate lines 121 and thedata lines 171. These edges are parallel or perpendicular to thepolarizing axes. This prevents the light leakage at the boundaries ofthe openings A, B and C.

A color filter array panel for an LCD according to the first embodimentwill be now described with reference to FIGS. 2 to 4.

A black matrix 220 preferably including double layers of Cr/CrOx isformed on a transparent glass substrate 210 and defines pixel areas. Aplurality of red, green and blue color filters 230R, 230G and 230B areformed in the respective pixel areas. An overcoat 250 covers andprotects the color filters 230R, 230G and 230B, and a common electrode270 preferably made of a transparent conductive material is formed onthe overcoat 250. The common electrode 270 has a plurality of sets offirst to third cutouts 271 to 273. The first cutout 271 bisects theupper or lower half of the pixel area into two portions arranged in thetransverse direction. The second and the third cutouts 272 and 273trisect the other upper or lower half of the pixel area into threeportions arranged in the longitudinal direction. Both ends of the eachcutout 271 to 273 are gradually enlarged to form an isosceles triangle.The first to the third cutouts 271 to 273 in two pixel areas adjacent inthe transverse direction are reversed in their positions in thelongitudinal direction.

Meanwhile, the black matrix 220 may be made of an organic insulatingmaterial containing a black pigment, instead of the metal such as Cr.

After the TFT array panel shown in FIG. 1 and the color filter arraypanel shown in FIG. 2 are aligned and assembled, a liquid crystalmaterial 3 is injected between the panels such that the long axes of theliquid crystal molecules are aligned perpendicular to the substrates 110and 210. An LCD according to the first embodiment is then prepared byattaching two polarizing plates 12 and 22 to outer surfaces of thesubstrates 110 and 210 such that the polarizing axes thereof cross eachother. The polarizing axes of the polarizing plates 12 and 22 make angleof about 45 degrees with respect to the gate lines 121 or the data lines171.

The substrates 110 and 210 are aligned such that the partitions 190 a to190 c of the pixel electrode 190 overlap the first to the third cutouts271 to 273 of the common electrode 270 to partition the pixel area intoa plurality of subareas. Each subarea has two long edges and two shortedges and is elongated parallel to the gate lines 121 or the data lines171.

Meanwhile, each partition 190 a to 190 c of the pixel electrode 190 hastwo long edges and two short edges. The long edges of each partitionextend parallel to the data lines 171 or the gate lines 121 and makeangle of about 45 degrees with the polarizing axes of the polarizingplates.

The storage electrode line 131 or the storage electrodes 133 a to 133 dare disposed between the data lines 171 or the gate lines 121 and thelong edges of the partition adjacent thereto. Meanwhile, it ispreferable that the storage electrode wire is not assigned near theshort edges of the partition, or spaced apart therefrom by at leastthree microns. Otherwise, the storage electrode wire is preferably fullycovered by the pixel electrode 190. This is because the electricpotential of the data lines 171 or the gate lines 121 close to the longedges of the partitions obstructs the domain formation. On the contrary,the electric potential of the data line 171 or the gate line 121 closeto the short edges of the partition make a contribution to the domainformation.

As shown in FIG. 3, the boundaries of the openings A, B and C in theprotective layer 180 and the gate insulating layer 140 have saw-toothededges parallel or perpendicular to the polarizing axes. This structurereduces the light leakage at the boundaries of the openings A, B and Cand this will be described in detail.

The liquid crystal molecules near the steps formed at the boundaries ofthe openings A, B and C are out of order. That is, the long axes of theliquid crystal molecules are not aligned perpendicular to the substrates110 and 210 but inclined thereto even in the absence of the electricfield and this may change the polarization of light to result in thelight leakage. However, if the tilt directions of the liquid crystalmolecule are parallel or perpendicular to the polarizing axes, the lightpolarization is not affected by the orientations of the liquid crystalmolecules. Meanwhile, the steps near the boundaries of the openings A, Band C tilt the liquid crystal molecules positioned close thereto to beperpendicular to the boundaries. Consequently, the long axes of theliquid crystal molecules become parallel or perpendicular to thepolarizing axes. In other words, although the liquid crystal moleculespositioned close to the boundaries of the openings A, B and C areoriented oblique to the substrates due to the stepped difference, thepolarization of the light is not affected since the tilt directions areparallel or perpendicular to the polarizing axes. Therefore, theincrease in the light leakage due to the openings A, B and C can beprevented.

A second embodiment of the present invention is described now.

FIG. 5 is a sectional view of an exemplary LCD according to a secondembodiment of the present invention taken along the line IV-IV′ in FIG.3. Green color filters G of the LCD have thickness larger than red colorfilters R and blue color filters B. This enable to satisfy a colorcorrection condition expressed in Equation 2.

For instance, the thickness of the green color filter G is larger thanthat of the other two color filters R and B by about 0.1-0.2 microns.The step between the green color filter G and the red and the blue colorfilters R and B has about 0.1 to 0.2 microns.

The assembly of the color filter array panel and the TFT array panelaccording to the first embodiment with a gap therebetween providesdifferent cell gaps for the respective pixel areas.

The B pixel area in the assembly protrudes toward the liquid crystallayer by about 0.5-0.7 microns compared with the R and G pixel areas,and the green color filter G corresponding to the C pixel area protrudestoward the liquid crystal layer by about 0.1-0.2 microns compared withthe red and blue color filters R and B corresponding to the R and Bpixel areas.

Therefore, the cell gaps of the respective pixel areas satisfy Equation2.

As described above, the present invention provides individual cell gapsfor the respective pixel areas to form multi cell gaps. The multi cellgaps enable to control the light transmittance of the respective pixelareas, thereby realizing the desired color correction.

Furthermore, the saw-toothed shapes or the zigzag shapes of theboundaries of the openings A, B and C reduce the light leakage near theboundaries.

It is preferable that a plurality of spacers, particularly in pillarshapes, are provided between the TFT array panel and the color filterarray panel to maintain the uniform distance therebetween. The spacersare preferably positioned at the areas covered by the black matrix 110.

A method of fabricating the TFT array panel will be now described withreference to FIGS. 6A to 6E as well as FIG. 1.

FIGS. 6A to 6E are sectional views of the TFT array panel shown in FIG.1 according to the first and the second embodiments taking along thelines VI-VI′, VI′-VI″ and VI″-VI″′, which sequentially illustrate theintermediate steps of fabricating the TFT array panel.

As shown in FIG. 6A, a gate metal layer is deposited on an insulatingsubstrate 110 and patterned by photo etching to form a gate wire. Thegate wire includes a plurality of gate lines 121, a plurality of gateelectrodes 123, and a plurality of gate pads 125.

Thereafter, as shown in FIG. 6B, a gate insulating layer 140 made of aninsulating material such as silicon nitride is deposited on theinsulating substrate 110 such that it covers the gate wire 121, 123 and125.

An amorphous silicon layer and a conductive-impurity-doped amorphoussilicon layer are sequentially deposited on the gate insulating layer140, and patterned by photo etching to form an amorphous silicon layer151 and 153 and an ohmic contact layer 160 and 161.

As shown in FIG. 6C, a data metal layer is deposited on the entiresurface of the substrate, and patterned by photo etching to form a datawire. The data wire includes a plurality of data lines 171, a pluralityof source electrodes 173, and a plurality of drain electrodes 175. Thedata lines 171 intersect the gate lines 121 to define a plurality ofpixel areas including R pixel areas, G pixel areas, and B pixel areas.

The ohmic contact layer 161 and 160 is etched using the source and thedrain electrodes 173 and 175 as a mask such that it is divided intoportions 163 contacting the source electrodes 173 and portions 165contacting the drain electrodes 175.

As shown in FIG. 6D, a protective layer 180 preferably made of siliconnitride or silicon oxide is formed on the entire surface of thesubstrate provided with the data wire 171, 173, 175 and 179 and thesemiconductor pattern 151 and 153.

The protective layer 180 and the gate insulating layer 140 are patternedby photo etching to form a plurality of contact holes 181, 182 and 183respectively exposing the drain electrodes 175, the gate pads 125 andthe data pads 179, and a plurality of openings A, B and C exposing theinsulating substrate 110 in the R and G pixel areas.

As shown in FIG. 6E, a transparent conductive layer made of ITO or IZOis deposited on the entire surface of the substrate, and patterned byphoto etching to form a plurality of pixel electrodes 190 in therespective pixel areas. The pixel electrodes 190 are connected to thedrain electrodes 175 through the contact holes 181. In this process, aplurality of subsidiary gate pads 95 and a plurality of subsidiary datapads 97 are formed together with the pixel electrodes 190 such that theycover the gate pads 125 and the data pads 179, respectively.

The color filter array panel of the LCD according to the firstembodiment is fabricated by the usual process.

However, the second embodiment forms green color filters G to be thickerthan red and blue color filters R and B.

That is, a black matrix 220 is formed on a top substrate 210, and aplurality of red, green and blue color filters R, G and B aresequentially formed thereon as shown in FIG. 5. The color filters may beformed by sequentially repeating the steps of coating one of red, greenand blue color resins on the substrate and performing selective lightexposure and development. The green color resin coated on the substratepreferably has a relatively large thickness such that the green colorfilter G is thicker than the R and B color filters. An overcoat 250 isformed on the substrate to cover the entire surface of the substrate,and a common electrode 270 is formed thereon.

FIG. 7 is a layout view of a LCD according to a third embodiment of thepresent invention, and FIG. 8 is a sectional view of the LCD shown inFIG. 7 taken along the line VIII-VIII′.

The LCD has a bottom substrate 110, a top substrate 210 facing thebottom substrate 110, and a liquid crystal layer 3 interposed betweenthe bottom substrate 110 and the top substrate 210 such that liquidcrystal molecules in the liquid crystal layer are aligned perpendicularto the substrates 210 and 220. The bottom and the top substrate 110 and210 are made of an insulating material such as transparent glass.

A plurality of pixel electrodes 190 are formed on the bottom substrate110. The pixel electrodes 190 is made of a transparent conductivematerial such as indium tin oxide (ITO) and indium zinc oxide (IZO) andhave a plurality of apertures 191, 192 and 193. Each pixel electrode 190is connected to a TFT to receive image signal voltages. The TFT isconnected to a gate line 121 for carrying scanning signals and a dataline 171 for carrying image signals to switch on/off the pixel electrode190 responsive to the scanning signals. Furthermore, a bottom polarizingplate 12 is attached to outer surface of the bottom substrate 110. Thepixel electrodes 190 of a reflective type LCD may not be made of atransparent material and the reflective type LCD does not require thebottom polarizing plate 12.

A black matrix 220 for preventing light leakage, a plurality of red,green and blue color filters 230 and a common electrode made oftransparent material such ITO and IZO are formed on the top substrate210. The common electrode 270 is provided with a plurality of sets ofcutouts 271 to 273. The black matrix 220 may located on the cutouts 271to 273 as well as the periphery of pixel areas for preventing lightleakage due to the cutouts 271 to 273.

The LCD according to the third embodiment will be now described in moredetail.

A plurality of gate lines 121 extending in a transverse direction areformed on the bottom insulating substrate 110. A plurality of gateelectrodes 123 protrudes from the gate lines 121. A plurality of storageelectrode lines 131 extending parallel to the gate lines 121 are formedon the insulating substrate 110. Each storage electrode line 131 isconnected to a plurality of pairs of storage electrodes 133 a and 133 bextending in a longitudinal direction and connected to each otherthrough a storage electrode 133 c extending in the transverse direction.At least one additional storage electrode lines 131 may be provided. Thegate lines 121, the gate electrodes 123, the storage electrode lines 131and the storage electrodes 133 a to 133 c are made of a metal such as Aland Cr, and have a single-layered structure or a double-layeredstructure including sequentially-deposited Cr and Al layers. The gatewire and the storage wire may be made of various metals.

A gate insulating layer 140 preferably made of silicon nitride is formedon the gate lines 121, the storage electrode lines 131 and the storageelectrodes 133 a to 133 c.

A plurality of data lines 171 extending in the longitudinal directionare formed on the gate insulating layer 140. A plurality of sourceelectrodes 173 branched from each data line 171 and a plurality of drainelectrodes 175 positioned close to the source electrodes 173 are formed.A plurality of bridge metal pieces 172 overlapping the gate lines 121are formed on the gate insulating layer 140. Like the gate wire, thedata lines 171, the source electrodes 173 and the drain electrodes 175are preferably made of Cr or Al, and may also have a single-layeredstructure or a double-layered structure.

A plurality of channel portions 151 of an amorphous silicon layer usedas channels of TFTs are formed under the source and the drain electrodes173 and 175. A plurality of data portions 153 of the amorphous siliconlayer are formed under the data line 171 such that they interconnect thechannel portions 151 of the amorphous silicon layer in the longitudinaldirection. A plurality of ohmic contacts (not shown) are formed on thechannel portions 151 of the amorphous silicon layer for reducing thecontact resistance between the source and drain electrodes 173 and 175and the channel portions 151 of the amorphous silicon layer. The ohmiccontacts are made of amorphous silicon heavily doped with n-typeimpurity.

A protective layer 180 preferably made of an inorganic insulatingmaterial such as silicon nitride or an organic material such as resin isformed on the data lines 171. The protective layer 180 is provided witha plurality of contact holes 181 exposing the drain electrodes 175.

The protective layer 180 and the gate insulating layer 140 are providedwith a plurality of openings A, B and C having saw-toothed edges. Theopenings A, B and C are formed by removing the protective layer 180 andthe gate insulating layer 140 by etching.

A plurality of pixel electrodes 190 having a plurality of apertures191-193 are formed on the protective layer 180. The pixel electrodes 190are made of a transparent conductive material such as ITO and IZO, or anopaque conductive material exhibiting excellent light reflectance suchas Al. The apertures 191 to 193 of the pixel electrodes 190 include atransverse aperture 192 extending in the transverse direction andbisecting the pixel electrode 190 into two portions arranged in thelongitudinal direction and a plurality of oblique apertures 191 and 193located in upper and lower halves of the pixel electrode 190 andextending obliquely. The apertures 191 and 193 placed in the upper andlower halves of the pixel electrode 190 are perpendicular to each other.This is to uniformly distribute the fringe fields in four directions.

The pixel electrodes 190 in the red and the green pixel areas overlapthe openings A, B and C of the protective layer 180 and the gateinsulating layer 140 such that they contact the substrate 110 in theopenings A, B and C. The openings A, B and C are not provided in theblue pixel area such that the pixel electrode 190 in the blue pixel areais placed on the protective layer 180.

The apertures 191 to 193 of the two pixel electrodes 190 opposite eachother with respect to the data line 171 have an inversion symmetry.

A plurality of storage connection bridges 91 are also formed on theprotective layer 180 such that they interconnects the storage electrodes133 a and the storage electrode lines 131 across the gate line 121. Thestorage connection bridge 91 contacts the storage electrode 133 a andthe storage electrode line 131 through the contact holes 183 and 184formed in the protective layer 180 and the gate insulating layer 140.The storage connection bridge 91 overlaps the bridge piece 172. Thestorage connection bridge 91 electrically interconnects the storage wirecomponents on the bottom substrate 110. If needed, the storage wire maybe used to repair the defects of the gate lines 121 or the data lines171. The bridge pieces 172 are provided for assisting the electricalconnection between the gate lines 121 and the storage connection bridges91 formed by laser shorting for the repair.

A black matrix 220 for preventing light leakage is formed on the topinsulating substrate 210. A plurality of red, green and blue colorfilters 230 are formed on the black matrix 220. A common electrode 270having a plurality of cutouts 271, 272 and 273 is formed on the colorfilters 230. The common electrode 270 is made of a transparentconductive material such as ITO and IZO.

The oblique apertures 191 and 193 of the pixel electrode 190 areinterposed between the cutouts 271 to 273 of the common electrode 270,which include oblique portions extending parallel to the obliqueapertures 191 and 193, and bent portions overlapping the edges of thepixel electrode 190. The bent portions are classified into transversebent portions and longitudinal bent portions.

The cutouts 271 to 273 of the common electrode 270 in the two pixelareas opposite each other with respect to the data line 171 haveinversion symmetry.

The LCD according to this embodiment is prepared by aligning andassembling the TFT array panel and the color filter array panel andinjecting a liquid crystal material into a gap between the two panelssuch that the liquid crystal material is subject to vertical alignment.The apertures 191 to 193 of the pixel electrode 190 and the cutouts 271to 273 of the common electrode 270 in the assembly of the TFT arraypanel and the color filter array panel aligned with each other partitiona pixel area into a plurality of domains. The domains are classifiedinto four classes depending upon the average long axial directions ofthe liquid crystal molecules.

According to the above-described embodiments, the gate insulating layer140 and the protective layer 180 are left in the B pixel area, whilethey are removed in the R and G pixel areas. However, upper part of thegate insulating layer 140 in the pixel areas may be removed such thatlower part of the gate insulating layer 140 and the protective layer 180are left in the B pixel area, and the gate insulating layer 140 and theprotective layer 180 are all removed at the R and G pixel areas.Furthermore, the gate insulating layer 140 in the B pixel area may beall removed while leaving out the protective layer 180.

In order to obtain such a structure, the etching time for etching theamorphous silicon layer 151 and 153 and the ohmic contact layer 161, 163and 165 is increased to over-etch upper part of the underlying gateinsulating layer 140 or all of the gate insulating layer 140. Theremaining process steps are performed as in the first and the secondembodiments.

The arrangement of the cutouts of the pixel electrodes and the commonelectrode may be modified in various manners. Protrusions may beprovided instead of the cutouts.

As described above, the inventive LCD differentiates the cell gaps forthe respective pixel areas to separately control the light transmittancein the respective pixel areas, thereby realizing the desired colorcorrection. Furthermore, the boundaries of the openings for controllingthe cell gap have zigzag shapes, which prevent light leakage near theboundaries.

Although preferred embodiments of the present invention have beendescribed in detail hereinabove, it should be clearly understood thatmany variations and/or modifications of the basic inventive conceptsherein taught which may appear to those skilled in the present art willstill fall within the spirit and scope of the present invention, asdefined in the appended claims.

1. A liquid crystal display comprising: a first insulating substrate; aplurality of gate lines formed on the first insulting substrate; a gateinsulating layer covering the gate line; a plurality of data linesformed on the gate insulating layer and intersecting the gate lines todefine first to third pixel areas; a plurality of thin film transistorselectrically connected to the gate lines and the data lines; aprotective layer covering the thin film transistors and the data linesand having a plurality of contact holes exposing a plurality of drainelectrodes of the thin film transistors; a plurality of pixel electrodesconnected to the drain electrodes through the contact holes; a secondinsulating substrate facing the first insulating substrate; a blackmatrix having a plurality of openings formed on the second insulatingsubstrate; red, green, and blue color filters each arranged within anopening of the black matrix and arranged on the second insulatingsubstrate, wherein the red, green, and blue color filters face the firstto third pixel areas; and a common electrode covering the red, green,and blue color filters and having a plurality of cutouts disposed on thered, green, and blue color filters, wherein the protective layer and thegate insulating layer have openings in the first and the second pixelareas, wherein the protective layer and the gate insulating layer do nothave openings in the third pixel area, wherein the openings of theprotective layer and gate insulation layer overlap the pixel electrodes,and wherein the green color filter that is arranged within an opening ofthe black matrix is thicker than both the red color filter arrangedwithin an opening of the black matrix and the blue color filter arrangedwithin an opening of the black matrix.
 2. The liquid crystal display ofclaim 1, wherein a portion of the gate insulating layer overlapping asemiconductor pattern is thicker than other portions of the gateinsulating layer.
 3. The liquid crystal display of claim 1, wherein eachof the plurality of pixel electrodes includes a plurality of partitions,and each of the openings of the gate insulating layer includes aplurality of sub-portions overlapping the partitions of the pixelelectrodes.
 4. The liquid crystal display of claim 1, wherein a cell gapD1 in the first pixel area, a cell gap D2 in the second pixel area, anda cell gap D3 in the third pixel area satisfy the relation: D1>D2>D3. 5.The liquid crystal display of claim 1, further comprising an overcoatformed between the common electrode and the color filters.
 6. The liquidcrystal display of claim 1, wherein the openings of the protective layereach have zigzag-shaped boundaries.
 7. The liquid crystal display ofclaim 6, wherein the boundaries of the openings of the protective layereach form an angle of about 45 degrees or about 135 degrees with respectto the gate lines.
 8. The liquid crystal display of claim 6, wherein theboundaries of the openings of the protective layer each form an angle ofabout 90 degrees with respect to the gate lines.
 9. A method ofmanufacturing a liquid crystal display, comprising: forming a gate wireincluding a gate line and gate electrodes on a first insulatingsubstrate; forming a semiconductor pattern on a gate insulating layer;forming a data wire including a data line defining a first, second, andthird pixel area by crossing the gate line, and defining sourceelectrodes and drain electrodes connected to the semiconductor pattern;forming a passivation layer covering the semiconductor pattern and thedata wires; forming contact holes exposing the drain electrodes andopenings in the first and second pixel areas of the gate insulatinglayer and the passivation layer; forming pixel electrodes connected tothe drain electrodes through the contact holes; forming a black matrixhaving a plurality of openings on a second insulation substrate; formingred, green, and blue color filters each within an opening of the blackmatrix and arranged on the second insulating substrate, wherein the red,green, and blue color filters face the first to the third pixel areas;forming a common electrode on the red, green, and blue color filters,wherein the common electrode has a plurality of cutouts disposed on thered, green, and blue color filters; and assembling the first substrateand the second substrate, wherein the passivation layer and the gateinsulating layer each have openings over the first and second pixelareas, wherein the passivation layer and the gate insulating layer donot have openings over the third pixel area, wherein the openings of thepassivation layer and the gate insulating layer overlap the pixelelectrodes, and wherein the green color filter that is arranged withinan opening of the black matrix is thicker than both the red color filterarranged within an opening of the black matrix and the blue color filterarranged within an opening of the black matrix.
 10. The liquid crystaldisplay of claim 1, wherein the red color filter arranged within theopening of the black matrix is substantially equal in thickness to theblue color filter arranged within the opening of the black matrix. 11.The method of claim 9, wherein the red color filter arranged within theopening of the black matrix is substantially equal in thickness to theblue color filter arranged within the opening of the black matrix.